Cushion hitch for motor grader

ABSTRACT

A cushion hitch having a hydraulic cylinder coupled to a vertical link and an extendable rod coupled to the front of a motor-grader type machine. The cushion hitch allows for both articulation and vertical movement. The cushion hitch helps reduce bounce and pitch in the motor-grader type machine—having a front frame and a rear frame—by controlling the supply of hydraulic fluid to the hydraulic cylinder.

TECHNICAL FIELD

The present disclosure generally relates to cushion hitches, and more particularly relates to a cushion hitch that improves the ride quality at an operator station of a sectional machine such as a motor grader.

BACKGROUND

A motor grader is a versatile apparatus that finishes various types of uneven surfaces. As can be expected, the uneven surfaces create disparate types of forces acting on the motor grader. These disparate forces create bounce vibrations that may adversely affect an operator's comfort level by propagating through the motor grader to the operator. The bounce may also interrupt the contact between work surfaces and the motor grader's moldboard which may result in an uneven finish or scallop on the work surface—requiring reworking of the work surface or the application of additional material for proper finishing. Additionally, a pitch and/or bounce vibration may manifest itself during certain operations of the motor grader in which the moldboard may not be in contact with the work surface, such as high speed travel.

The magnitude of the vibration is a function of numerous physical characteristics of the motor grader such as its weight distribution, pitch and bounce inertia, the distance between the rear wheels and the moldboard, tire characteristics, as well as the machine operating conditions.

Motor graders often include complex joint couplings to help provide versatile steering capabilities, but fail to compensate for bounce vibrations. For example, U.S. Pat. No. 8,282,306B2 discloses a joint between two vehicle components joined to each other with a hinge, such as an articulated vehicle including an articulated joint. The joint segments of U.S. Pat. No. 8,282,306B2 are connected by a tensioning device and bearings are interposed between the articulated joint and the vehicle.

The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Consequently, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described in the disclosure are defined by the appended claims.

SUMMARY

In one aspect, the present disclosure provides a cushion hitch. The cushion hitch includes a vertical link coupled to a rear frame of a machine and an upper pivotable link coupled to the vertical link and to a front frame of the machine. The cushion hitch also includes a lower pivotable link coupled to the vertical link and to the front frame of the machine. The cushion hitch further includes a hydraulic cylinder coupled to the vertical link. The hydraulic cylinder has an extendable rod coupled to the front of the machine.

In another aspect, the present disclosure provides a motor-grader machine including a front frame attached to an operator station and a rear frame having a power system. The rear frame being coupled to a vertical link. The motor-grader machine also includes an upper pivotable link coupled to the vertical link and to the front frame, as well as a lower pivotable link coupled to the vertical link and to the front frame. The motor-grader machine further includes a hydraulic cylinder assembly having an extendable rod. The hydraulic cylinder assembly is coupled to the vertical link and the extendable rod is coupled to the front frame.

In yet another aspect, the present disclosure provides a method for reducing bounce in a motor-grader machine having a front frame and a rear frame. The method includes controlling the supply of hydraulic fluid to a hydraulic cylinder coupled to a vertical link that is coupled to the rear frame of the motor-grader machine where the hydraulic cylinder has an extendable rod coupled to the front frame of the motor-grader machine.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a motor grader within which one or more embodiments of the present disclosure may be implemented;

FIG. 2 is a schematic top view of a motor grader within which one or more embodiments of the present disclosure may be implemented;

FIG. 3 is a schematic side view of a cushion hitch in accordance with an aspect of the disclosure; and

FIG. 4 is a schematic top view of a cushion hitch in accordance with an aspect of the disclosure.

While the disclosure is susceptible to various modifications and alternative forms, specifics have been shown by way of example in the drawings and will be described in detail below. It should be understood that the detailed description is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the disclosure covers all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

The present disclosure relates to a cushion hitch that provides articulation as well as vertical movement between a front frame and a rear frame of a sectional machine such as a motor grader. Wherever possible the same reference numbers will be used throughout the drawings to refer to the same or like parts. Moreover, references to various elements described herein are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. Accordingly, it may be noted that any such reference to elements in the singular is also to be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.

FIG. 1 is a schematic side view of a motor grader 10 in accordance with one embodiment of the present disclosure. The motor grader 10 includes a front frame 12, rear frame 14, and a work implement blade 16, e.g., a blade assembly 18, also referred to as a drawbar-circle-moldboard assembly (DCM). The rear frame 14 includes a power source (not shown), contained within a rear compartment 20, that is operatively coupled through a transmission (not shown) to rear traction devices or rear wheels 22 for primary machine propulsion. As shown, the rear wheels 22 may be operatively supported on tandems 24 which are pivotally connected to the machine between the rear wheels 22 on each side of the motor grader 10.

The power source may be, for example, a diesel engine, a gasoline engine, a natural gas engine, or any other engine known in the art. The power source may also be an electric motor linked to a fuel cell, capacitive storage device, battery, or another source of power known in the art. The transmission may be a mechanical transmission, hydraulic transmission, or any other transmission type known in the art. The transmission may be operable to produce multiple output speed ratios (or a continuously variable speed ratio) between the power source and driven traction devices.

The front frame 12 supports an operator station 26 that contains operator controls, along with a variety of displays or indicators used to convey information to the operator, for primary operation of the motor grader 10. The front frame 12 also includes a beam 28 that supports the blade assembly 18 and is employed to move the blade 30 to a wide range of positions relative to the motor grader 10. The blade assembly 18 includes a drawbar 32 pivotally mounted to a first end 34 of the beam 28 via a ball joint (not shown). The position of the drawbar 32 is controlled by three hydraulic cylinders: a right lift cylinder 36 and left lift cylinder 38 (FIG. 2) that control vertical movement, and a center shift cylinder 40 that controls horizontal movement. The right and left lift cylinders 36, 38 are connected to a coupling 70 that includes lift arms 72 pivotally connected to the beam 28 for rotation about axis C. A bottom portion of the coupling 70 has an adjustable length horizontal member 74 that is connected to the center shift cylinder 40.

The drawbar 32 includes a large, flat plate, commonly referred to as a yoke plate 42. Beneath the yoke plate 42 is a circular gear arrangement and mount, commonly referred to as the circle 44. The circle 44 is rotated by, for example, a hydraulic motor referred to as the circle drive 46. Rotation of the circle 44 by the circle drive 46 rotates the attached blade 30 about an axis A perpendicular to a plane of the yoke plate 42. The blade 30 cutting angle is defined as the angle of the work implement blade 16 relative to a longitudinal axis 48 of the front frame 12. For example, at a zero degree blade cutting angle, the blade 30 is aligned at a right angle to the longitudinal axis 48 of the front frame 12 and beam 28 (FIG. 2).

The blade 30 is also mounted to the circle 44 via a pivot assembly 50 that allows for tilting of the blade 30 relative to the circle 44. A blade tip cylinder 52 is used to tilt the blade 30 forward or rearward. In other words, the blade tip cylinder 52 is used to tip or tilt a top edge 54 relative to the bottom cutting edge 56 of the blade 30, which is commonly referred to as blade tip. The blade 30 is also mounted to a sliding joint associated with the circle 44 that allows the blade 30 to be slid or shifted from side-to-side relative to the circle 44. The side-to-side shift is commonly referred to as blade side shift. A side shift cylinder (not shown) is used to control the blade side shift.

Motor grader 10 course direction is accomplished through a combination of both front wheel steering and machine articulation. As shown in FIG. 2, steerable traction devices, right and left wheels 58, 60, are associated with the first end 34 of the beam 28. Front wheels 58, 60 may be both rotatable and tiltable for use during steering and leveling of a work surface 86 (FIG. 1). Front wheels 58, 60 are connected via a steering apparatus 88 that may include a linkage 90 and a hydraulic cylinder (not shown) for rotation about front wheel pivot points 80, FIG. 3, and tilt cylinders 92 for front wheel tilt. The front wheels 58, 60 may also be driven, as is the case in motor graders provided with all-wheel drive. For example, the power source may be operatively connected to a hydraulic pump (not shown) fluidly coupled to one or more hydraulic motors (not shown) associated with the front wheels 58, 60.

Having generally discussed an overview of motor grader 10, embodiments of the cushion hitch 62 will now be discussed in more detail. Cushion hitch 62 allows articulation, as well as vertical movement between the front frame 12 and the rear frame 14 of motor grader 10. FIG. 3 shows a side view of an embodiment of the cushion hitch 62 located between front frame 12 and rear frame 14. As discussed above, front frame 12 supports an operator station 26 that contains operator controls, along with a variety of displays or indicators used to convey information to the operator, for primary operation of the motor grader 10. The rear frame 14 includes a power source (not shown), contained within a rear compartment 20, that is operatively coupled through a transmission (not shown) to rear traction devices or rear wheels 22 for primary machine propulsion. Front frame 12 is coupled to rear frame 14 via vertical link 105, upper pivotable links 104, and lower pivotable links 102. Vertical link 105 couples the upper pivotable links 104 and lower pivotable links 102 to rear frame 14 using one or more vertical pivot pins 108. The vertical link 105, upper pivotable links 104, and lower pivotable links 102 may be formed of a rigid material, such as steel, iron, or other high tensile strength metallic material. In the alternative, it is contemplated that the vertical link 105, upper pivotable links 104, and lower pivotable links 102 may be formed of a composite material, such as Kevlar, carbon graphite, or other high strength materials.

The upper pivotable links 104 and lower pivotable links 102 couple front frame 12 with vertical link 105 that couples to rear frame 14 at pivot points 106. The pivot points 106 may include a pin or other holding device that passes through openings in the vertical link 105, upper pivotable links 104, and lower pivotable links 102, as well as through openings in front frame 12 and rear frame 14. Cushion hitch 62 may include at least one articulation cylinder 107. Articulation cylinder 107 couples to rear frame 14 and includes an articulation extendable rod 111 that couples to vertical link 105 with at least one vertical pivot pin 108 that allows for articulation of cushion hitch 62. Pressurized fluid (e.g., a hydraulic fluid) being controlled by a control valve 122 may provide extension and retraction of extendable rod 112 as discussed below in reference to hydraulic cylinder assembly 110. As should be readily understood, such a configuration of the cushion hitch 62 allows for articulation and vertical pivoting motion along multiple planes and axis between front frame 12 (attached to an operator station 26) and rear frame 14 (including the power source).

As shown in FIG. 3, a hydraulic cylinder assembly 110, having an extendable rod 112, is disposed between and coupled to front frame 12 and vertical link 105—as will be discussed in more detail with reference to FIG. 4. As extendable rod 112 extends, a ride height of front frame 12 is raised. Conversely, as extendable rod 112 retracts, the ride height of front frame 12 is lowered. Extension and retraction of extendable rod 112 may be provided via a pressurized fluid being controlled by a control valve 122. To extend extendable rod 112 of hydraulic cylinder assembly 110, control valve 122 receives pressurized fluid from a fluid pump 123. Fluid pump 123 passes the pressurized fluid through a fluid line 124, a variable orifice assembly 126, hydraulic cylinder assembly 110, fluid line 127 and tank return fluid line 129, and then to a fluid tank return/holding tank 130. As should be understood, the fluid system is generally a closed loop fluid system where the operable fluid is pressurized to perform a work function and then is returned to be used again.

In some embodiments, control valve 122 may actively direct energy in the form of pressurized hydraulic fluid to extend or retract hydraulic cylinder assembly 110—thereby directly varying the amount of energy dissipated or provided to the cushion hitch 62. In other embodiments, control valve 122 electrically communicates with variable orifice assembly 126 to influence the speed at which extendable rod 112 extends and contracts. Variable orifice assembly 126 may include a variable orifice 128 and fixed restrictive elements such as a first check valve assembly 150 and a second check valve assembly 152 in series with the variable orifice 128. A variable orifice controller 140 may provide operation signals such as electrical, pressurized fluid, or other communication signals to the variable orifice 128 and control valve 122. The variable orifice controller 140, in communication with control valve 122, can control the size of the variable orifice 128. The operation signals cause the variable orifice 128 to increase and/or decrease the size of the fluid passageway through the variable orifice 128. The size change influences or otherwise controls a resistance to the pressurized fluid flowing through the variable orifice 128. This, in turn, influences or otherwise controls the damping or energy dissipated by the extension and retraction of extendable rod 112 of the hydraulic cylinder assembly 110. Accordingly, an extension and retraction rate for extendable rod 112 can be tuned to provide an optimized hitch rigidity and an optimized machine efficiency, in balance with operator ride comfort. While FIG. 3 shows variable orifice assembly 126 configured to include variable orifice 128 in series with first check valve assembly 150 and second check valve assembly 152 formed in a block manifold—the components of variable orifice assembly 126 may also be formed using individual components fluidly coupled together.

Variable orifice controller 140 provides operation signals such as electrical, pressurized fluid, or other communication signals to variable orifice 128. The operation signals cause the variable orifice 128 to increase and/or decrease the size of the passageway through variable orifice 128. The size change of the fluid passageway influences or otherwise controls a resistance to the pressurized fluid flowing through the variable orifice 128. Accordingly, variable orifice controller 140 may be tuned to help influence or otherwise controls the damping or energy dissipated by the extension and retraction of extendable rod 112.

If variable orifice 128 does not respond to control signals from variable orifice controller 140 or otherwise fails to operate, the fluid opening may float anywhere along an operating range for the variable orifice 128. As mentioned above, first check valve assembly 150 and second check valve assembly 152 may be fluidly coupled in series with variable orifice 128. First check valve assembly 150 includes a first fixed orifice 142 and a first choke/check valve 144 in parallel with one another, and in series with variable orifice 128. Similarly, second check valve assembly 152 includes a second fixed orifice 148 and a second choke/check valve 146 in parallel with one another, and in series with variable orifice 128. First choke/check valve 144 and second choke/check valve 146 may be biased check valves requiring fluid to reach a pre-determined pressure to open the valve and pass through.

Control valve 122 may lock extendable rod 112 into a fully retracted location, a fully extended location, and/or at any location in between. One or more accumulators 132 are fluidly coupled with the control valve 122 via an accumulator fluid line 134. Accumulator 132 is a fluid tank having a free-floating piston, bladder, or other device that divides accumulator 132 into different chambers. One chamber is for the pressurized fluid and one chamber is for a compressible gas (e.g., nitrogen). Accumulator 132 receives the pressurized fluid in the fluid chamber, which displaces the piston or bladder, to help compress the gas in the gas chamber. For example, if the motor grader 10 hits a bump or hole while driving, extendable rod 112 is likely to be forced to extend or retract very quickly as shock of the bump or hole is transferred between front frame 12 and rear frame 14. This passes the pressurized fluid through control valve 122 and to or from accumulator 132. This allows hydraulic cylinder assembly 110 to help dissipate the shock/energy rather than passing it between front frame 12 and rear frame 14.

FIG. 4 shows a top view embodiment of the cushion hitch 62 located between front frame 12 and rear frame 14. Front frame 12 is coupled to rear frame 14 via vertical link 105, upper pivotable links 104 and lower pivotable links 102 (FIG. 3). Vertical link 105 couples the upper pivotable links 104 and lower pivotable links 102 (FIG. 3) to rear frame 14 using one or more vertical pivot pins 108. hydraulic cylinder assembly 110, having an extendable rod 112, is disposed between and coupled to front frame 12 and vertical link 105 via pivot pin 109 a coupled to front frame 12 and pivot pin 109 b coupled to a lower portion of vertical link 105.

Although the present disclosure discloses that the cushion hitch 62 is part of motor grader 10, one of ordinary skill in the art will appreciate that the cushion hitch 62 may be beneficially implemented with other similar machines. Therefore, various combinations of the parts disclosed herein may be contemplated and such combinations can be implemented without deviating from the spirit of the present disclosure.

INDUSTRIAL APPLICABILITY

The cushion hitch 62 of the present disclosure has applicability for implementation and use in industrial settings such as agriculture, construction, and the like.

The present disclosure provides motor grader 10 that includes a cushion hitch 62. In operation, motor grader 10 creates flat surfaces (generally to finished grade) during a grading process opposed to rough grading performed by other machines such as scrapers. Cushion hitch 62 reduces shock and vibration felt by an operator of motor grader 10 during the grading process by providing articulation and vertical movement.

The hydraulic cylinder assembly 110 including extendable rod 112 in combination with the upper pivotable links 104 and lower pivotable links 102 help enable the cushion hitch 62 to dissipate energy transferred to the operator station 26 of the motor grader 10. Control valve 122 permits extendable rod 112 to extend and retract and may provide active control. Moreover, control valve 122 may be employed to keep extendable rod 112 at a mid-range extension length to help provide hydraulic cushion suspension with cushion hitch 62.

Variable orifice assembly 126 helps provide a controlled operation for extension and retraction speeds of extendable rod 112 as instructed by variable orifice controller 140. Variable orifice controller 140 may employ variable orifice 128 to provide different damping rates for different operations of motor grader 10. For example, when grading softer materials, variable orifice 128 may be smaller to restrict the movement of extendable rod 112. Conversely, when grading harder materials, variable orifice 128 may be larger, allowing extendable rod 112 to extend and retract more freely.

If variable orifice 128 does not respond to instructions from variable orifice controller 140, first choke/check valve 144 and second choke/check valve 146 provide fixed tuning for extension and retraction speeds for extendable rod 112. If variable orifice 128 is not active or is not operational, fluid pressure at variable orifice assembly 126 may force variable orifice 128 fully open and may consequently allow a higher fluid flow rate through variable orifice assembly 126. Accordingly, first fixed orifice 142 and second fixed orifice 148 provide a flow rate that is lower than the non-active flow rate of variable orifice 128. Under certain circumstances, first fixed orifice 142 and second fixed orifice 148 flow rates may differ from one another.

When extendable rod 112 is extended, fluid flows from control valve 122 through fluid line 124, through first fixed orifice 142, through variable orifice 128, and through second fixed orifice 148 to hydraulic cylinder assembly 110, then to fluid line 127 and back to control valve 122. Once fluid pressure reaches a desired pressure, the fluid will overcome biasing pressure of second choke/check valve 146 and also flow through second choke/check valve 146. First choke/check valve 144 forces fluid to flow through first fixed orifice 142 when extendable rod 112 is extending. When extendable rod 112 is retracted, fluid flows from control valve 122 through fluid line 127, through hydraulic cylinder assembly 110, through second fixed orifice 148, through variable orifice 128, and through first fixed orifice 142, then to fluid line 124 and back to control valve 122. Once fluid pressure reaches a desired pressure, the fluid will overcome biasing pressure of first choke/check valve 144 and will also flow through first choke/check valve 144. Second choke/check valve 146 forces fluid to flow through second fixed orifice 148 when extendable rod 112 is retracting. Accordingly, flow rates for extension and retraction of extendable rod 112 may be adjusted when variable orifice 128 is not active or responsive to variable orifice controller 140.

It should be understood that the above description is intended for illustrative purposes only. In particular, it should be appreciated that all methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present invention as determined based upon the claims below and any equivalents thereof. 

1. A cushion hitch, comprising: a vertical link coupled to a rear frame of a machine; an upper pivotable link coupled to the vertical link and to a front frame of the machine; a lower pivotable link coupled to the vertical link and to the front frame of the machine; and a hydraulic cylinder coupled to the vertical link, the hydraulic cylinder having a rod coupled to the front frame of the machine at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.
 2. The cushion hitch of claim 1, further comprising a control valve operatively associated with the hydraulic cylinder for controlling fluid into and out of the hydraulic cylinder.
 3. The cushion hitch of claim 2, wherein the control valve is operably associated with a variable orifice assembly.
 4. The cushion hitch of claim 3, wherein the variable orifice assembly comprises a variable orifice and a check valve assembly in series.
 5. (canceled)
 6. The cushion hitch of claim 4, further comprising a control valve for controlling fluid into and out of the at least one articulation cylinder.
 7. The cushion hitch of claim 1, wherein the vertical link is coupled to the rear frame of the machine using one or more vertical pivot pins.
 8. A motor-grader machine, comprising: a front frame attached to an operator station; a rear frame having a power system, the rear frame being coupled to a vertical link; an upper pivotable link coupled to the vertical link and to the front frame; a lower pivotable link coupled to the vertical link and to the front frame; and a hydraulic cylinder assembly having an extendable rod, wherein the hydraulic cylinder assembly is coupled to the vertical link and the extendable rod is coupled to the front frame at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.
 9. The motor-grader machine of claim 8, further comprising a control valve fluidly coupled to the hydraulic cylinder assembly, wherein the control valve is configured to adjust an extension length of the extendable rod.
 10. The motor-grader machine of claim 9, further comprising a variable orifice fluidly coupled to the control valve, wherein the variable orifice is configured to adjust resistance to extension and retraction of the extendable rod.
 11. The motor-grader machine of claim 10, wherein a size of the variable orifice is electrically controlled.
 12. The motor-grader machine of claim 10, further comprising a check valve assembly in series with the variable orifice.
 13. (canceled)
 14. The motor-grader machine of claim 12, further comprising a control valve for controlling fluid into and out of the at least one articulation cylinder.
 15. The motor-grader machine of claim 1, wherein the vertical link is coupled to the rear frame of the machine using one or more vertical pivot pins.
 16. A method for reducing bounce in a motor-grader machine having a front frame and a rear frame, comprising: controlling a supply of hydraulic fluid to a hydraulic cylinder coupled to a vertical link that is coupled to the rear frame of the motor-grader machine, the hydraulic cylinder having an extendable rod coupled to the front frame of the motor-grader machine at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.
 17. The method of claim 16, wherein controlling a supply of hydraulic fluid comprises adjusting a resistance to extension and retraction of the extendable rod with a variable orifice.
 18. The method of claim 17, wherein adjusting the resistance with the variable orifice is performed electronically.
 19. The method of claim 16, wherein controlling a supply of hydraulic fluid comprises adjusting a resistance to extension and retraction of the extendable rod with a variable orifice in series with a check valve assembly.
 20. The method of claim 19, wherein adjusting the resistance with the variable orifice in series with the check valve assembly is performed electronically. 